I updated some photos of my contacts in Thunderbird 31.7.0. The synchronization doesn't detect these changes and don't synchonize de photos to my Samsung Note 4 (Lolipop).
Did you experience this issue ?
The BirdieSync support doesn't answer to my question to this issue.

I've answered to you. It may be related to the default photo maximum size defined in BirdieSync options (Thunderbird menu "Tools/BirdieSync/Options...", Contact panel, Miscellaneous tab).
Try to increase it to 500KB (don't put a too high value because of the limited memory on your mobile device).
Modify your contact and try to synchronize again.